core: Release log for 0.5.2
core: Release log for 0.5.2

Tarnyko/rygel,Tarnyko/rygel,jku/rygel,jku/rygel,luisbg/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched